Bunashimeji mushroom named &#39;hkhm25&#39;

ABSTRACT

The present variety of Bunashimeji mushroom named ‘HKHM25’ was cultivated by the gathering and repeated breeding of Bunashimeji mushrooms having thick and elastic stems, dark cap color, strong cap roll, and a large mushroom size, has a high quality and enhanced cultivation stability. This edible mushroom is exquisite in stability, reproducibility and uniformity when being produced.

BACKGROUND OF THE INVENTION

This invention relates to a new and distinct variety of Bunashimeji mushroom, Hypsizygus marmoreus (Peck) H. E. Bigelow. This new variety named ‘HKHM25,’ cultivated by repeated breeding of Bunashimeji mushroom having thick and elastic stems, dark cap color, strong cap roll, and a large mushroom size, has a high quality and enhanced cultivation stability, and ensures presentable stability, reproducibility, and uniformity.

The annual production of Bunashimeji mushrooms is approximately 120,000 tons in 2020, making it the second most consumed edible mushroom after enokitake mushroom in Japan. However, since Bunashimeji mushrooms have become available in large quantities in the market, Bunashimeji mushrooms with improved flavor, quality and shelf life has been pursued, which led to the development of ‘Hokuto 18gokin’ by our company. Further, our company has been conducting a wide variety of studies for the more stable cultivation and better quality of Bunashimeji mushrooms. Our company has developed a ‘marmo22go’ mushroom which is thicker, whiter, and has larger mushroom than ‘Hokuto 18gokin’.

Further, using ‘marmo22go’ as a parent, as a result of continuing breed improvement by cross breeding to improve stability and quality, ‘HKHM25’, which has thicker stems and stronger cap roll, as compared to ‘marmo22go’, was developed, confirming its stability, reproducibility, and uniformity.

SUMMARY OF THE INVENTION

The present invention is a new and distinct variety of mushroom plant characterized particularly by having thick and elastic stems, dark cap color, strong cap roll, and a large mushroom size, which can be cultivated by gathering and repeated breeding of fungal strains having a stability, reproducibility and uniformity when being produced. This novel and distinct variety of mushroom is identified as ‘HKHM25’.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a phylogenetic tree illustrating the antecedents of ‘HKHM25’.

FIG. 2A and 2B respectively show front and back images of a dual-culture of ‘HKHM25’.

FIG. 3A and 3B respectively show front and back images of a dual-culture of ‘HKM25’ and ‘Hokuto 18gokin’.

FIG. 4A and 4B respectively show front and back images of a dual-culture of ‘HKHM25’ and ‘marmo22go’.

FIG. 5A and 5B respectively show front and back images of a fungal flora of ‘HKHM25’ grown in a petri dish.

FIG. 6A and 6B respectively show front and back image of a fungal flora of ‘Holcuto 18gokin’ grown in a petri dish.

FIG. 7A and 7B respectively show front and back images of fungal flora of ‘marmo22go’ grown in a petri dish.

FIG. 8 shows an image of cultivation area of ‘HKHM25’.

FIG. 9 shows an image of cultivation area of ‘Hokuto 18gokin’.

FIG. 10 shows an image of cultivation area of ‘marmo22go’.

FIG. 11 shows an image of a fruit body of ‘HKHM25’.

FIG. 12 shows an image of a fruit body of ‘Hokuto 18gokin’.

FIG. 13: shows an image of a fruit body of ‘marmo22go’.

FIG. 14 shows an image of density and surface color of fungal flora in cultured hyphae of ‘HKHM25’.

FIG. 15 shows an image of density and surface color of fungal flora in cultured hyphae of ‘Hokuto 18gokin’.

FIG. 16 shows an image of density and surface color of fungal flora in cultured hyphae of ‘marmo22go’.

FIG. 17 shows an image of development of aerial hypha of ‘HKHM25’.

FIG. 18 shows an image of development of aerial hypha of ‘Hokcuto 18gokin’.

FIG. 19 shows an image of development of aerial hypha of ‘marmo22go’.

FIG. 20 shows an image of size and distribution of mottle of ‘HKHM25’.

FIG. 21 shows an image of size and distribution of mottle of ‘Hokuto 18gokin’.

FIG. 22 shows an image of size and distribution of mottle of ‘marmo22go’.

FIG. 23 shows an image of shape and thickness of stipe of ‘HKHM25’.

FIG. 24 shows an image of shape and thickness of stipe of ‘Hokuto 18gokin’.

FIG. 25 shows an image of shape and thickness of stipe of ‘marmo22go’.

DETAILED DESCRIPTION OF THE INVENTION

The history of the ‘HKHM25’ mushroom in terms of improvement period and the like are set forth in the following chronological list of each stage of variety improvement:

-   -   December 2014: Cultivation of ‘MH025615’ strain.     -   January 2017: Cultivation of ‘MH025617’(‘marmo22go’) strain.     -   December 2019: ‘MH025615’ and ‘MH025617’ (‘marmo22go’) strains         were crossed and a strain with thick stem, strong cap roll, and         good quality among the obtained strains was selected as         ‘MH025633’. We then repeated the cultivation test to distinguish         the strains.     -   March 2021: After repeated cultivation tests, since         distinguishability, stability, and uniformity were confirmed,         the strain was named ‘HKHM25’ and its cultivation was completed.         Applied for registration of a new variety to the Ministry of         Agriculture, Forestry and Fisheries of Japan.

The above crossing is summarized in the phylogenetic tree illustrated in FIG. 1.

The ‘HKHM25’ mushroom has the following characteristics: thick and elastic stems, dark cap color, strong cap roll, and overall large size.

-   (1) Comparison with existing variety by dual culture: Dual culture     was performed for the ‘HKHM25’ mushroom and a similar variety to     examine whether or not a zone line is formed.     -   -   Study method.—As an examination method, a potato dextrose             agar medium was used, and the ‘HKHM25’ mushroom and the             similar variety were inoculated thereon face to face at an             interval of 3 cm, and then culture was performed at 25° C.             for 28 days to examine whether or not a zone line was             formed.         -   Strain used.—‘HKHM25’:Present variety. ‘Hokuto 18gokin’:             Variety similar to the present variety. ‘marmo22go’: Parent             variety of the present variety.         -   Results.—Zone lines were formed between ‘HKHM25’ and all             other co-cultured varieties (Table 1, FIGS. 2 to 4). This             clearly shows that the present mushroom is a new variety.

Similar varieties Hokuto 18gokin marmo22go HKHM25 + + + is present and − is absent. *Zone line formation was not observed in the dual culture between ‘HKHM25’ strains.

-   (2) Growth characteristics of ‘HKHM25’:     -   -   Study method.—After inoculating an agar piece of the             ‘HKHM25’ having a diameter of 5 mm and an agar piece of the             similar variety having a diameter of 5 mm on a potato             dextrose agar medium, preculture was performed at 25° C. for             4 days so as to make the regeneration of hyphae equal (about             10 mm in diameter), and then culture was performed for 7             days at intervals of 5° C. between 5° C. and 30° C. An             average daily hyphae growth rate was calculated based on a             hyphae growth rate for 7 days of the culture.         -   Results.—‘HKHM25’ had the fastest average daily hyphae             growth rate at 20° C. In addition, HKHM25 had slower             mycelial growth rate than ‘Hokuto 18gokin’ and ‘marmo22go’             at each temperature zone (Table 2). -   (3) Morphological characteristics of the ‘HKHM25’ mushroom in a     cultivation example:     -   -   Cultivation method.—Container: An 850 polypropylene bottle             (Capacity: 850 ml, diameter 58 mm) was used. Culture medium:             Conifer sawdust, corn cob, rice bran and wheat bran were             mixed at the dry weight ratio of 7:3:8:2, and the water             content was adjusted to 65%. The culture medium was filled             up to the brim of the bottle at the rate of 540±20 g per             bottle, and was sterilized at high pressure. Starter             culture: About 20 ml of sawdust starter cultures per bottle             was inoculated. Culture: Culture was performed at 22° C. for             50 to 90 days at 70% moisture. Growth: After completing the             culture, the inoculum is removed, and shifted to a growing             room. Development was conducted under a temperature of             15±1° C. at humidity of 95% or about 2,000 ppm CO₂ density.             Also, light was not particularly irradiated until the first             14th day, then irradiated with about 500 to 1,000 Lx. The             mushroom is harvested when the cap in the center of the             stump has sufficiently opened.         -   Cultivation results.—Table 2 shows the characteristics of             the ‘HKHM25’ and specific difference in characteristics as             compared with the similar variety when culture was performed             under the abovementioned conditions.

TABLE 2 Fungus characteristics Table of Hypsizygus marmoreus (Peck) H.E.Bigelow of Recording and Registration

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What is claimed is:
 1. A new, distinct variety of Bunashimeji Mushroom as substantially illustrated and described in the specification. 